Today we will try to give you a quick overview on the GIF file format.
GIF format was introduced by CompuServe in 1987 and soon became widely adopted because it supported colours (unlike its CompuServe predecessor, RLE) and it was small-sized (thanks to the LZW lossless compression algorithm, we’ve told you a story about that in a previous article), allowing reasonably fast file transfers even for the slow, dial-up modems era.
CompuServe was a company way ahead of its time.
It was founded in Columbus, Ohio, in 1969 (the « prehistory » of the internet) by an insurance company (« Golden United Life Insurance »), initially to provide computing power for in-house optimization of the data-management needs of the mother company but shortly CompuServe became a serious business on its own, some naming it « the Google of the 70’s and 80’s ».
First they rented computing power time to other companies (when computers were idle), then a long series of pioneering achievements followed, here is an incomplete enumeration: one of the first companies to offer online services, world’s first online service offering internet connectivity, issued and hosted thousands of moderated forums, created a file transfer protocol, developed its own (proprietary) email services, hosted the first WYSIWYG email and forum posts content, pioneered the online shopping, created customized portals, pioneered online financial services, created an online chat system, introduced online games and published the first online newspaper and the first online comics.
And invented GIF, of course.
GIF (« Graphics Interchange Format ») is a bitmap graphics file format, its first version being referred to as GIF 87a, to indicate the year of release, 1987.
Two years and many enhancements later, GIF 89a version was introduced and it accounts for the vast majority of GIFs currently existing on the internet.
It provides image designers with 256 colors, allows multiple images storage for animation purposes (not in the sense of multipage, as in TIFF), provides controls for animation (animation speed and single/infinite loop option), allows on-or-off transparency (no intermediary gradients of transparency, as in PNG), provides lossless compression and introduced interlacing as an option.
Interlacing, when it concerns image files, means the image is gradually rendered by a browser but rendering starts immediately after download starts so, at first, the image looks unclear, like being out of focus, then, as its download continues, it becomes sharper and sharper, finally showing in full quality when image download is complete.
Previously described Progressive JPEG and the soon to be described PNG formats provide optional interlacing feature, too, but while in GIF and Progressive JPEG case interlacing changes the rendering order of the horizontal lines, the PNG format allows changing the order both horizontally and vertically.
As for compression, GIF uses the LZW lossless compression algoritm eversince it was created.
LZW was a perfect fit for its 8-bits-per-pixel color encoding (ie, maximum 256 colors displayed at one time in a frame) as well as for the animation feature, because GIF animation works by successively displaying bitmap images slightly different from one another (frames), their most part remaining unchanged so, being repetitive, most data are subject to very efficient compression by LZW.
GIF format isn’t commonly used for photos because compressing only 256 colors, even in a lossless manner, provides much poorer results than lossy compressing some 16 millions colors, like JPEG does.
Although the LZW algorithm was/is a major contributor to GIF’s popularity and widespread, it also gave it almost 10 years of torment (since about 1994 until about 2004) caused by the Unisys patent protection controversy.
But nowadays GIF format enjoys times of peace and recognition which will probably continue to last as long as people will keep their apetite for logos, icons, animated emoticons, low-res short clips, educational animated clips and so forth.
In 2012, this venerable format received public tribute from the Oxford Dictionaries USA subsidiary of Oxford University Press, the word « GIF » being granted the « Word of the Year » title, both as a noun and as a verb.
So now the question is: to GIF or not to GIF ?
We will try to answer this shakespearian question in a future article about which bitmap format fits best for which purpose, as PaperScan supports them all.
See you next week!